In a large heavy skillet, over medium heat, saute celery and onion with 2 tablespoons oil, for 5 to 8 minutes. Add the frozen vegetables and cook another 5 minutes. Add flour and cook about 30 seconds.

Add chicken broth and bring to a boil. After it has become thick, add potatoes.

Remove chicken from pot and cut into bite-size pieces and add to vegetable mixture. Add salt and pepper to taste.

Pour mixture into a 9 inch deep dish pie plate and cover with pie shell. Make sure you crimp the edges of the pie shell to the plate so no juices spill in oven.

Bake at 350 degrees F (175 degrees C) for 45 minutes or until pie shell is cooked and golden brown.